It is known, as in U.S. Pat. No. 5,531,192 which issued Jul. 8, 1996, to provide a spring closed poppet valve with an hydraulic actuator connected to an electrically motivated valve selecting a high or a low fluid pressure source for a cylindrical plunger chamber which extends through a cylindrical body and in which a plunger reciprocates. This actuator controls poppet valve closing by restricting fluid flow from the plunger chamber to the low pressure source. At final valve closing, this flow is restricted by an orifice, which is bypassed by a first check valve during poppet valve opening, after initially restricting the closing flow through a second check valve to which flow is gradually cut off by a frusto-conical end of the plunger. In this actuator, opening ports and the second check valve open radially through the body, and the orifice and the first check valve are disposed in the plunger centrally of its frusto-conical end and communicate with the closing check valve through an annular chamber about the plunger. The second check valve and opening ports communicate with an annular body chamber connected to the electrically motivated valve, and the opening ports are disposed to communicate with the annular plunger chamber when the poppet valve is closed. On poppet valve opening, The second check restricts fluid flow to the opening ports.
It is also known, as in U.S. Pat. No. 5,562,070 which issued Oct. 8, 1996, to provide such an actuator for a unitary poppet valve and piston, where the valve is both opened and closed by fluid forces, with a check valve which opens for fluid to be pushed from a volume above the piston into a high pressure source during valve seating to avoid the possibility of hard impact during valve seating.
It is thus evident that, in the actuators disclosed by these patents, the various check valve and fluid communication arrangements serve to control poppet valve closing speed and impact rather than to recuperate the kinetic energy of the poppet valve and actuator elements moving therewith during closing and thus reduce the power required to operate poppet valves.